Dual rate liquid atomizing apparatus and dual firing rate oil burner embodying the same



Filed April 4, 1951 April 14, 1953 P. H. BILLS ETAL 2,634,805

DUAL RATE LIQUID ATOMIZING APPARATUS AND DUAL FIRING RATE OIL. BURNEREMBODYING THE SAME 4 Sheets-Sheet 1 BY IM ATTORNEYS Apnl 14, 1953 P. H.BILLS ETAL 2,634,805

I DUAL RATE LIQUID ATOMIZING APPARATUS AND DUAL FIRING RATE OIL. BURNEREMBODYING THE SAME Filed April 4, 1951 4 Sheets-Sheet 2 ATTORNEYS April14, 1953 P. H. BILLS ETAL 2,634,805 DUAL RATE LIQUID ATOMIZING APPARATUSAND DUAL FIRING RATE OIL BURNER EMBODYING THE SAME 4 Sheets$heet 3 FiledApril 4, 1951 I i'IJ ism:

ATTORNEYS d. 3 r Z 3 Apnl 14, 1953 P. H. BILLS ETAL 2,634,305

DUAL RATE LIQUID ATOMIZING APPARATUS AND DUAL FIRING RATE OIL BURNEREMBODYING THE SAME Filed April 4, 1951 4 Sheets-Sheet 4 v 11 k m g M;/49

ATTORNEYS Patented Apr. 14, 1953 UNITED STATES PATENT OFFICE DUAL RATELIQUID ATOMIZING APPARATUS AND DUAL FIRING RATE OIL BURNER EM- BODYINGTHE SAME Application April 4, 1951, Serial No. 219,188

3 Claims. 1

This invention relates to the atomization of liquids by means of amechanical or pressure atomizing nozzle at more than one rate, whensupplied with liquid by an electromagnetically-controlledreciprocating-piston pump, the piston of which reciprocates atrelatively high frequency, say for example, at 3600 cycles per minute.

The invention is capable of general application. However, it finds onevery important specific use in connection with the atomization of liquidfuel in pressure-atomizing oil burners of the class adapted forhouse-heating service, where operation at more than one rate isdesirable, as for example, at a relatively high rate during the moresevere weather and at a relatively low rate during milder weather.

Burners of this class, heretofore, have secured the two firing rateseither by providing two nozzles, each having its own oil supply with apressure-regulating valve to maintain the pressure constant at aselected value, or by providing one nozzle and pressure-regulating valvemeans which can be actuated to vary the pressure of the oil supplied tothe one nozzle from one to the other of two selected values. The firstarrangement has the disadvantage that one nozzle is idle while the otheroperates, whereby carbonization at and near the idle nozzle can occur,eventually resulting in nozzle stoppage, unless special and ratherelaborate provisions are provided to prevent such action. The secondarrangement has the disadvantage that a wide range in the two pressuresis necessary in order to secure the desired spread in the two firingrates and the high pressure is not readily obtained with theconventional gear type pump unless a relatively low pressure is used forthe low rate and then the low pressure is too low to secure goodatomization from the nozzle alone. The fundamental difficulty is thatthe rate of oil delivery from a mechanical atomizing nozzle varies asthe square root of the pressures. Doubling the oil pressure increasesthe rate of oil delivery only 40 per cent, approximately. If one wishesto use, as the lower pressure, a good atomizing pressure, such as 100 p.s. i., then the higher pressure would have to be 200 p. s. i., in orderto secure a 40 per cent increase in the firing rate. The conventionalgear pump, usually used on oil burners of this class, is not adapted toproduce such a high pressure.

With an electromagnetically-controlled pump, wherein the pump pistonreciprocates at relatively high frequency, as for example at the 60cycle frequency of the alternating current supply, the desired spread inoil pressures is readily obtained. Pumps of this type, one example ofwhich is disclosed in our copending application, Serial No. 189,741,filed October 12, 1950, have a stroke, which is variable according tothe power applied and the load encountered. On this account, thepressure of the pumped liquid varies rapidly with variations in linevoltage, as much, for example, as 4 p. s. i. per volt variation in theelectrical supply. This necessitates the use of a regulator in order tomaintain the pressure at the mechanical atomizing nozzle substantiallyconstant at a predetermined value. Assuming that normal line voltage is115 volts, it is necessary, as a practical matter, to maintain thepressure at the nozzle substantially constant over a range ofapproximately 29 volts or from 98 to 127 volts. A voltage variation ofthis magnitude would, unless compensated for, cause a variation of 116p. s. i., in the pressure of the pumped oil. Ordinarypressure-regulating valves, such as are commonly used in the oil supplyline of pressure-atomizing oil burners, are not suitable for use with apump of the type described for the purpose of maintaining the pressureof the pumped oil substantially constant at either of the selectedvalues. For example, when such a valve is used and it opens at thepredetermined pressure, the pump at once operates at full stroke andbecomes very noisy. Also, the opening of the by-pass unloads the pump. Asecond outlet is provided by the opening of the by-pass valve, whichoutlet is relatively large in comparison with the tiny opening of thenozzle, and the pump has not enough capacity to supply the amount of oilnecessary through both these openings at the same time to build up andmaintain the pressure desired. While the pressure of the pumped liquidmay be readily varied by varying the voltage applied to the magnet coilof the pump, this method is not feasible to use with a regulator, whichacts to maintain the current at such coil substantially constant. Theinsertion of a resistor in series in the circuit to drop the voltagewill have the effect of making the regulator try to maintain the currentconstant at the magnet coil and the desired effect of reduced currentflow through the coil will not be obtained.

This invention has for its object the provision in anelectromagnetically-controlled pump of the class described, having aregulator which functions to maintain the current in the magnet coilsubstantially constant over a predetermined range of variations in linevoltage, of

means that can be connected in shunt with the magnet coil, whenever alower pumping pressure is desired, in order to divert some of thecurrent from the magnet coil and thus cause the pump to operate at alower pressure. Thus, a divided circuit is provided for low rateoperation and the regulator maintains the same total current, as it doesfor high rate operation, but part of the current is diverted through theshunt. This shunt should have approximately the same power factor as theelectromagnet in order that the current wave in each branch of thedivided circuit should have the same phase relation with the voltagewave.

The invention has for another object the provision of a dual rate oilburner, which has an oil pump of the type described with a regulator formaintaining substantially constant current and in which the two oilpressures are secured by the use of the shunt. as above described,together with means for changing the rate of air flow to the burnerproportionately with the change in rate of oil flow in order to securegood combustion at either the relatively high or the relatively lowrate.

These and other objects will best be understood from the detaileddescription of one illustrative example of the invention in theaccompanying drawings, in which:

Fig. 1 is a side elevational view of an oil burner embodying theinvention;

Fig. 2 is a sectional elevational view taken on the line 2--2 of Fig.and drawn to a larger scale;

Fig. 3 is a rear elevational view of the burner;

Fig. 4 is a fragmentary cross sectional view taken on the line -d ofFig. 1;

Fig. 5 is a sectional plan view taken on the line 55 of Fig. 1;

Fig. 6 is a sectional elevational view taken on the line 66 of Fig. 3;

Fig. '7 is a cross sectional view taken on the line 7-7 of Fig. 5;

Fig. 8 is a fragmentary side elevational view, taken oppositely to Fig.1 and showing a manual control for changing the firing rate of theburner;

Fig. 9 is a fragmentary view taken at right angles to Fig. 8; and

Figs. 10 and 11 are wiring d agrams showing respectively the automaticand manual firing rate control.

In these drawings, there has been shown for illustrative purposes asingle example of a guntype pressure-atomizin oil burner adapted forhouse heating service. This burner will serve as a background for theinvention, wh ch has to do with provisions for operating a burner ofthis general type at either of two selected firing rates. The details ofthe burner structure shown are not essential to the invention which maybe embodied in any burner of the pressure-atomizing type.

The particular burner structure illustrated includes an air supply fan I(Fig. 6), mounted in a casing 2, which is suitably supported, as by afioor plate 3 and an adjustable post 4. Casing 2 (see Fig. 4) hasopenings 5 and 6 in opposite end walls i and 8, respectively, and has aperipheral outlet 9 (Fig. 6) leading into an air chamber Ill, whichoverlies the fan and to which one end of a tube II is connected. Thistube conducts all the air for combustion and has its other end open andadapted to discharge into a furnace. Near the discharge end of tube H isa pressure-atomizing nozzle l2, of the usual and well known form, forproducing a spray, when supplied with oil under a pressure greater thana predeterm minimum value. On the outer end of the tube 1 l is an airdirector I3 for turning the air stream into the oil spray emitted fromthe nozzle and in this tube is a turbulator for whirling the air, suchturbulator comprising a series of spiral vanes I l projecting inwardlyfrom an annular ring 15. The opening 5 in the fan casing 2 (Fig. 4)receives a frusto-conical air director It, the flanged outer end ofwhich is clamped to end Wall I by a ring ll, secured by screws It! tosuch wall. The opening l9, within the air director, forms the main airinlet for the fan. The other opening 6 is covered by a plate 20, whichis secured to end wall 8 by screws 2! and which has a plurality ofopenings 22 therethrough. The fan I has its hub fixed, as indicated, tothe shaft 23 of an electric motor 24. The latter is fixed to thedescribed plate 20 by screws 25, which pass through the plate and threadinto lugs 26 on the inner end wall of the motor. Between these lugs andthe end wall are passages 2'1, leading to the openings 22 and thus tothe interior of the fan casing. Thus, air is drawn in by the fan i,partly through the main inlet is, and partly through the auxiliaryinlet, comprising the passages 21 and holes 22, and forced out throughoutlet 9 (Fig. 6) into chamber IE! and from the latter through tube H,the air being whirled by the turbulator vanes Hi just before it isdirected by cone I3 into the oil spray emitted from the nozzle I2.

The rate at which air is supplied to tube II is variable by means of adamper 28 which is fixed to a shaft 29, rotatably mounted at its ends,one in each of the walls I and 8. Stops 3G and 3! are provided torespectively arrest the damper in its high rate and low rate positions.The stop 30 consists of a screw, threaded into a wall of casing l withits inner end so located as to be directly engaged by the right handface of the damper, when the latter is swung to the right into its highrate position. The stop 3i consists of a pin, fixed in the inner end ofa screw 32, which also is threaded into said wall of the casing I andpasses freely through a hole in the damper. This pin is so located as tobe engaged by the left hand face of the damper, when the latter is swunginto its low rate position as shown. The high and low rates areindependently adjustable by turning screws 30 and 32, which are providedwith fine pitch threads to enable precision adjustments to be manuallyeffected. Lock nuts 3-3 and 34 on screws 30 and 32, respectively, holdthe stops in their various positions of adjustment.

The damper 28 may be automatically moved from its high and low ratepositions by the following means. A spring 35, connected at one end tothe wall 8 of casing I and at the other end to a crank arm 36 fixed onone end of shaft 29, tends to move damper 28 against the high rate stop30. Movement of the damper is controlled by a small electric controlmotor 31 (Fig. 1), which is suitably fixed to a bracket 38, suitablysecured to wall '1. Motor 31 has a shaft 39, provided on its inner endwith a crank 49. This motor, when actuated by means to be described,turns shaft 39 one-half revolution and then stops. When again actuated,it turns another half revolution and stops. The crank 46 always comes torest in a vertical position either upstanding from shaft 39 as shown ordepending therefrom. The crank 49 is connected to a crank 4! on shaft 29by a wire 42 and a spring 43. With the crank 40 in its upper position asshown, the damper 28 is held its low rate position against the force ofspring 3.5. The spring 43 absorbs any overtravel of crank 46 after thedamper 28 has engaged stop 3|. Since the low rate position may be variedby manual adjustment, the crank 40 must have suflicient travel to movethe damper into the extreme left hand end of its range of adjustment.When crank 40 moves into its depending vertical position, the spring 35swings the damper into its high rate position against stop 35 and thespring is capable of movin the damper to the right beyond the presenthigh rate position into other high rate positions if desired. The wire42 and crank 4! are preferably encased in a housing 44 suitably fixed towall 1.

A control motor such as described is a standard article of commerce. Itmay be constructed as disclosed in Johnson Patent No. 1,835,307, grantedDecember 8, 1931, to Minneapolis-Honeywell Regulator Company.

The oil is supplied to nozzle 12 by an electromagnetically-controlledreciprocating-piston pump, which is mounted on the side wall 8 of thecasing 2, as shown in Figs. 3 and 5. This pump and the electromagnet,which actuates it, are mounted in a casing, comprising a main section 45(Fig. 3) and a cover 46. The main section and cover are respectivelyprovided with shoulders 41 and 48 (Fig. 2) and hubs 49 and D, projectingin opposite directions one from each of the shoulders. A grommet 5! ofrubber-like material encompasses each hub and abuts the adjacentshoulder. Each grommet has a circumferential groove in its outerperiphery to receive a part of a supporting arm 52 and a U-shaped clamp53 (Fig. 5), which is fixed at its ends to the arm by bolts 54. Botharms 52 project outwardly at right angles from a common support 55,which is fixed to casing 2 by screws 56.

Referring next to Fig. 2, the casing section 45 and cover 46 are made ofsuitable magnetic material, and as herein shown of cast iron. The upperportion of section 45 has a large cylindrical recess in which is mountedthe annular coil 5'! of the electromagnet. Section 45 has a hole coaxialwith the magnet recess and extending from the latter through the sectionto the bottom thereof and fixed, as by a drive fit, in this opening is arod 58 which is of suitable magnetic material and in which is formed thecylinder 59 of the pump. Rod 58 has an integral upward extension 60projecting through the central opening in coil 51 and forming the coreof the electromagnet. Slidable in cylinder 59 is a piston El, whichextends upwardly through core 60 and has fixed to its upper end, at alocation above the upper end of the core, an armature 62. The latterpreferably has a frusto-conical lower end to cooperate with thecomplementary-shaped recess in the upper end of the core 65. The cover46 has a central opening 64 therein, which slidably receives thearmature, and in this opening are a series of angularly-spacedlongitudinally-extending grooves 65 to allow liquid to pass thearmature. A spring 66, located in opening 64, acts between suitableseats, one on the end wall of the opening and one on the top of thearmature, encircling rod BI, and tends to move the armature downwardly.A similar spring 61, mounted at its ends in suitable seats in recessesin the bottom of the armature and the upper end of core 60, tends tomove the armature upwardly. The armature is balanced between these twosprings, which have the same dimensions and are under the same initialstress. The armature is shown in its rest position midway of its stroke.The mass of the armature 62 and rod 6! and the characteristics of thesprings 66 and 6'! are so selected as to have a natural period ofvibration substantially equal to the frequency of thealternating-current supply, to which the coil 51 is adapted to beconnected. As will be later described in detail, the coil 51 isconnected to a 115 volt, 60 cycle, alternating source through a suitablehalf-wave rectifier, whereby it is energized intermittently in pulses atthe rate of 3600 per minute. When coil 51 is energized, the armature 62will be drawn downwardly toward the core 60 to actuate piston 6| on itspressure stroke, the magnetic circuit extending through core 66, acrossan axial air gap to armature 62, through the latter and across a smallradial air gap to cover 46, outwardly through the cover in radiatingpaths to the annular shell which surrounds coil 51, downwardly throughthis shell and thence inwardly in radiating paths to the lower end ofcore 66. When coil 51 is deenergized in the inter val between twosuccessive energizing electric pulses, the armature 62 will move awayfrom the core 60 and above the rest position illustrated. The stroke ofthe pump is variable, depending on the power applied to the coil and theresistance or load encountered by the piston. The resonant springs 66and 6'! serve to keep the armature 62 and piston 6! in vibration withonly a small amount of assistance from coil 51, leaving the major partof the energy developed by the coil for the performance of useful work.

The pump cylinder 59 has an inlet port 68, communicating with a passage69, which is formed in section 45 and extends horizontally outward andthence vertically upward to a cylindrical space [0, formed in cover 46and located above coil 51. This space is connected by the describedpassages 65 and 64 to the oil inlet H, which connects with the hole 64by means of the central opening through the upper seat of spring 60.This inlet is connected by a suitable conduit, such as copper tubing 12,to a suitable oil supply tank (not shown), the tubing preferably havinga coil 13 therein. The coil 51 is suitably sealed off from theoil-containing chamber 16, as by a circular member 14, which closelyfits around core 60 and the peripheral wall of the coil-containingrecess and has inner and outer seal rings 15 to engage such core andwall. The pump cylinder is provided with an outlet valve, such as theball valve 76, which is held closed by a spring Tl, acting against aseat on the upper end of a screw 18. The latter is threaded into thelower end of member 58 and closes the lower end of the opening therein.The outlet valve 15 opens into an outlet chamber 19, formed in member58, and this chamber connects with an outlet passage 80.

The outlet passage delivers the pumped oil into a cylindrical chamber8|, formed in the lower part of casing 45. A cover 82, secured to thiscasing by screws 33, provides access to the chamher and has a centraltapped opening therein which receives an outlet conduit 84. Within thechamber 8|, is a block of suitable resilient material, which in thiscase, is composed of particles of ground cork held together by arubberlike binder. The block is square in cross section and its cornersengage the cylindrical wall of chamber 8|, leaving four longitudinalpassages for the oil. Protuberances 86 on the end walls of this chamberengage the ends of the block and hold them spaced from such end walls toenable. oil from passage 80 to flow outwardly to said longitudinalpassages and thence inwardly aesgeoc from the latter to the outlet pipe8 3. One purpose of this arrangement is to smooth out the pulsations inthe stream of pumped oil. The pressure of the pumped oil will vary, muchas the voltage and current of the alternating-current supply does, in aWave which rises from a minimum to a maximum and back again at thefrequency of the alternating-current. The higher instantaneouspressures, will compress the member 55 and, at the lower instantaneouspressures, the member 85 will expand. Thus, the peaks of the wave willbe removed and the valleys filled in so that the stream leaving throughpipe 86 will not have wide fluctuations in pressure. A very importantpurpose of the described arrangement is to keep the minimum oil pressureof the stream above the lower pressure limit of the atomizing nozzle I2.As is well known, when the pressure of the oil fed to a pressure ormechanical atomizing nozzle falls below a certain value, the nozzle willnot produce a spray. Hence, it is essential to provide a limiting meanswhich will maintain minimum pressures high enough to maintain the nozzleoperative for its spray producing function.

The one particular arrangement described for controllin the pressurepulsations is desirable and preferred. However, there are many otherways of accomplishing the same result. Th essential thing is that thereshall be in the discharge conduit of the pump some portion, which isexpansible and contractible with the pressure pulsations of the pumpedoil so as to make the pressure of the stream more nearly uniform andmaintain the necessary minimum pressure a ues. The effectiveliquid-containing volume of the chamber increases and decreases with theincreases and decreases in pressure of the oil and any otherconstruction of the discharge conduit, which will enable such increasesand decreases in volume, may be used for the purpose.

The outlet conduit 84 is connected to the atomizing nozzle [2. As shown,this conduit consists of a copper tube (Fig. l), which extends upwardlyfrom the outlet of the regulator, has a coil 88 formed therein and thenenters through a notch (Fig. 5) in the side wall of casing 2 into therear end of the chamber Ill. The tube 84 then extends forwardly inchamber It and is connected by a union 89 to the rear end of a tubularsupport 98. The nozzle i2 is connected to the front end of this support.

Adjacent the nozzl l2 are a pair of electrodes 9|, which are mounted ininsulators 92 and have their rear ends connected by wires 93 with thehigh tension terminals 94 (Fig, 6) of an ignition transformer, mountedin a case 95, fixed on t p of easing 2.

The nozzle [2, turbulator Hi, and electrodes 85 may be supported in anysuitable way in tube l l, desirably in a manner to permit convenientwithdrawal of these parts in assembled relation from the tube H and thealigned chamber l8, after the closure plate 96 for the rear end ofchamber l6 and its retaining screws 91 have been removed. To this end, apair of rods 98 are fixed at one end to the ring [5 of the turbulator,one at each of two diametrically opposite points thereon, and these rodsextend rearwardly in spaced, parallel relation through tube H andthrough chamber 59, terminating in outwardly-bent parts 95, the outerends of which are received one in each of two notches formed one in eachof two opposite side walls of the casing 2. The plate 9% retains theseends 99 in their notches. Fixed at its ends to rods 98 and spanning thespace between them, is a support I00 having a central hub, in wh ch thenozzle-supporting tube 953 is fixed, and two outer hubs in which theinsulators 92 are fixed. The support Hid also has a central dependinghub (Fig. 7), to which an air-distributing baffle Hill is fixed. It willbe clear that when plate 98 is removed, the ends 99 of rods 98 arereleased. The high tension Wires 93 may then be disconnected fromterminals 94 and the oil pipe 8'! may be disconnected by removing union89 or W2, after which the nozzle 52, its support 96, the electrodes 9iwith their insulators s2 and the turbulator i l-i 5, may be withdrawnfor inspection, cleaning or repair.

One of the controls for the electromagnet coil 51 is a switch I33 (Fig.4), the closing of which is delayed by a device responsive to the speedof the air supply fan i. This switch 293 is shown in Figs. 1 and 4 as amicro-switch, mounted on an angle-iron shelf I54 fixed to the end wallof a cylindrical case I65, having its other end closed by a disk coverlDS, secured by screws it? to the case. This case I95 is supported byfour an larly-spaced arms I08 (Fig. 3) from the described ring il,leaving openings H39 through which air may enter to the main inletopening it of the fan. The switch 5 83 has an actuating plunger I 59(Fig. 4) and suitable spring means (not shown), tending to move theplunger to the left into closed position. The switch plunger 5 iii isactuated by a plunger i H, which is slidably mounted in a hub on the endwall of case m5. This plun er ii! is shown held in its right hand andswitchopening position by the flanged and closed outer end of a tube H2,which is slidably mounted on a rod H3, which has a flanged end, fixed asindicated to the drive shaft 23 of motor 2 3. A spring H i encompassesrod i i3 and acts between the flange on the rod and the adjacent end oftube 1 l 2 to force the latter to the right and press the plunger Hi ofswitch N13 to open the switch. The flanges of rod H3 and tube H2 areinterconnected by flexible metal bands l l each having fixed to it at apoint between its ends a suitable weight I It.

When the shaft 23 reaches a predetermined speed, as nearly as feasibleto full speed of the motor 263, these weights H5 fly outwardly bycentrifugal force and deflect the bands H5 outwardly, drawing tube H2 tothe left until it allows the plunger H! to move to switch-closingposition and continuing to the left until it disengages from the plungeriii. A small sprin I I7 takes up the lost motion and holds plunger illin contact with plunger HE and out of contact with the outer end of therotatin tube 1 l2. Spring H7 is not strong enough to move the switchplunger HE] against its internal actuating spring (not shown).

Referring next to Fig. 10, the fan motor 24 and the primary N8 of theignition transformer 95 are connected in parallel to wires H5 3 and I29and are controlled by a room thermostat switch 2! by means of which wire1 29 may be connected to a wire 22. The wires H and iii? are adapted forconnection to a suitable source of alternating current such for exampleas a Volt, 60 cycle supply. The secondary l 23 of the i nitiontransformer is connected by the described wires 93 to the ignitionelectrodes 9!. When ther is a demand for heat, the room thermostatswitch l2! will close the circuit to fan motor 2t and the ignitiontransformer 95, whereby the fan i will be operated to supply air throughtube H and ignition sparks will be produced between the elec-- trodes 9|adjacent th oil-atomizing nozzle I2.

The starting of the electromagnetically-controlled oil-supply pump ispreferably delayed by the centrifugal switch I03, which closes onlyafter the air supply fan has acquired considerable speed. This switchcontrols a branch circuit from the wires I10 and I20, which circuitincludes the solenoid coil 51, a suitable half-wave rectifier I25, and acurrent-regulator. The latter is preferably of the type disclosed in thecopending application of Theodore J. Mesh, Serial No. 189,742, filedOctober 12, 1950, and consists of a series impedance, comprising asaturable reactor having a winding I26 and a core I21. A capacitor I anda resistor I29 are suitably coupled into the reactor winding. In thiscase, the capacitor and resistor are connected in series with a windmgI30 inductively related to the reactor winding I26 on core I21, wherebythe capacitor and resistor are coupled inductively to the reactorWinding I26. The arrangement is like an auto transformer in whichwinding I26 is the primary and windings I and I the secondary. The pumpcircuit includes a wire I3I between wire I20 and switch I03, a wire I32connecting the latter to one terminal of the reactor winding I26, a wireI33 connecting the other terminal of winding I26 to one terminal ofsolenoid 51, a wire I34 connecting the other terminal of solenoid 51 toone terminal of the rectifier I25, and a wire I35 connecting the otherterminal of such rectifier to the wire II9. When switch I03 closes, thecoil 51 will be energized and the pump piston will be reciprocated tosupply oil to nozzle I2 to mix with the air supplied by fan I and thismixture will be ignited and burn. Operation of the burner will continueuntil the demand for heat is satisfied when the room thermostat switchI2I will open and break the circuit to motor 24, solenoid 51 and primaryII8. As the fan motor 24 slows down, switch I03 will open and provide asecond break in the circuit of the oil pump somewhat before the airsupply from fan I ceases.

The purpose of the described series impedance is to maintain thepressure of the pumped oil substantially constant over a predeterminedrange of variations in line voltage. In general, the result is effectedby maintaining the current supplied to coil 51 substantially constant.The elements of the impedance are coupled in a resonant circuit in whichthe current surges back and forth and may rise to values several timesthe value of the current flowing in coil 51. Consequently, the core ofthe reactor can become magnetically saturated by the circulatory currentin this resonant circuit before it could become saturated by the pumpcurrent flowing at normal line voltage in the circuit of coil 51. Thecore of the reactor is so designed as to become substantiallymagnetically saturated by such circulatory current as flows in theresonant circuit when resonance exists. This occurs when the linevoltage is at some selected predetermined value which may be, andpreferably is, normal line voltage, in this case 115 volts. At suchvoltage, the capacitative reactance and the inductive reactance withinthe resonant circuit have minimum values, which balance, and theeffective impedance in such circuit is wholly resistive and at itsminimum value. As line voltage decreases from normal, the reactancewithin the resonant circuit becomes capacitative and the effectiveimpedance increases as line voltage decreases until a certain lowervoltage limit is reached. As line voltage increases from normal thereactance within the resonant circuit becomes inductive and increases asthe Voltage increases until a certain upper voltage limit is reached.Beyond the upper voltage limit, the inductive reactance within theresonant circuit does not materially change and beyond the lower voltagelimit the effective capacitative impedance within such circuit does notmaterially change.

Having in mind that the coil 51 is energized intermittently in pulses,the pressure of the pumped oil can be changed by varying the duration ofeach pulse to offset the change effected by voltage variation, which isto increase or decrease the amplitude of the pulse as the current risesor falls. For example, a decrease in line voltage from normal, whichwould otherwise result in a decrease in current and a decrease in thestroke of the pump with a resulting drop in oil pressure, can be oifsetto some extent by introducing capacitative reactance into the circuit ofthe coil 51. Such reactance has a tendency to prolong each pulse, makingits duration somewhat more than the normal of a second in the case of 60cycle power. Similarly, an increase in line voltage from normal, whichwould ordinarily result in an increase in current in the coil 51 and anincrease in the stroke of the pump with a resulting increase in oilpressure, can be offset to some extent by introducing into the circuitof the coil 51 inductive reactance, which tends to shorten the pulses.Thus, at normal line voltage, the reactor and capacitor are in resonanceand only the resistor, which is of constant value, is in the circuit ofthe coil 51. On an increase in line voltage from normal, inductivereactance is introduced to offset the effect of the voltage increase andprogressively so as the voltage increases until the upper voltage limitis reached, when the inductive reactance is at its highest. On adecrease in line voltage from normal, capacitative reactance isintroduced to counteract the effect of decreasing current by lengtheningout the pulses and progressively so as the voltage decreases until thelower voltage limit is reached and the capacitative impedance reachesits maximum value. The resistor has the effect of providing a smoothtransition from inductive reactance to capacitative reactance and viceversa and broadens out the range over which the resonant circuit iseffective to change the pressure of the pumped oil.

The resonant circuit provides counter E. M. F. in the circuit to coil 51and such counter E. M. F. is variable to some extent with line voltagevariations so that the E. M. F. impressed on the coil 51 is modified tosome extent by the variable voltage drop in the circuit of the reactorand this is to some extent a factor in accomplishing the result desired.

In the particular arrangement shown in Fig. 10, the capacitor I28 has acapacity of 30 mfd., the resistor I29 a resistance of 20 ohms, thewinding I26 is composed of 400 turns of No. 21 wire, and the winding I30is composed of 2000 turns of No. 33 wire. Core 23 consists of about 30laminations of standard commercial transformer punchings N0. E I-15 ofsilicon steel, each of about .018 of an inch in thickness. These valuesare not critical and are given as illustrative examples and not asimposing limitations.

The rectifier I25 preferably has a resistor I35 shunted across it forthe purpose of permitting the flow of a small amount of current in thereverse direction between successive pulses for the purpose ofdemagnetizing and preventing sticking of the armature to its poles.

For causing the pump to operate at another rate and supply oil at adifferent pressure. which has to be maintained substantially constantover the same range of variations in line voltage, a shunt has beenprovided for the coil 51 of the pump, which shunt can be cut in circuitwith the coil whenever a lower oil pressure is desired. This shunt ispreferably an inductance, indicated at I31, and preferably also itshould have approximately the same power factor as the coil 51 of thepump, in this case around 50%. With this circuit, which is supplied withalternating current and which includes a rectifier I25 with a resistiveshunt I36, a regulator including a transformer, a capacitor I28 and aresistor I29, and the coil 51 of the magnetic pump with the inductiveshunt I31 for such coil, it is possible to maintain the oil pressure atthe nozzle I2 substantially constant at 200 p. s. i. ever the describedrange of variations in line voltage when the shunt is cut out of circuitand to maintain the oil pressure at such nozzle substantially constantat a pressure of 100 p. s. i. when the shunt I31 is connected incircuit. The burner may thus have a normal firing rate when suppliedwith oil at 100 p. s. i. and this rate can be increased 40% when theburner is supplied with oil at 200 p. s. i. to secure the high rateneeded for better heating in severe cold weather. The impedances of thecoil 51 and the shunt I3? should be, in this case, in the ratio of l to3 in order to divert approximately 25% of the output current of theregulator from the coil 51.

The inductive shunt I51 may be cut into and out of circuit by a switch,which is operated automatically from, and may be and preferably isincluded in, the control motor 51. This switch and the electricalcomponents of the control motor are shown diagrammatically in Fig. 10.This motor has a field winding I38, a rotor I39 a rotor shaft I45,gearing I II which connects shaft I40 to the described shaft 39, anddrums I52 and I43 fixed on shaft 39. The drum I52 has one half itssurface of insulating material I 44 and the other half of conductingmaterial I55 (suitably insulated from shaft 39). Two brushes I 56 and I51 engage the periphery of drum I52 and, when the control motor ispositioned as shown, these brushes engage the conducting part I45. Awire I58 connects brush I56 to one terminal of coil 51, a wire I55connects the other terminal of coil 51 to one terminal of the inductiveshunt I31 and a wire I50 connects the other terminal of the shunt tobrush I51. Thus, the inductive shunt I31 is connected in shunt circuitwith coil 51, when the control motor is in the illustrated and lowfiring rate position. When the motor is actuated to turn the shaft 39one half revolution, the non-conducting part I 35 of drum I52 will bemoved in under the brushes I46 and I41 and cause the inductive shunt tocut out of circuit to enable the pump to deliver oil at the high rate.

The control motor 31 may be controlled by any suitable means. Oneillustrative example is an outdoor thermostat switch I i which, when theweather is mild, say 20 Fahr. or above, will engage a contact I52 and,when the weather is severe, say below 20 Fahr., will engage a contactI53. This thermostat switch controls a low voltage circuit, such as a 24volt circuit, to the field winding I38 of the control motor 31. Thus,the switch I5I is connected by a wire I 55 to one terminal of thesecondary I55 of a step-down transformer, the primary I56 of which is atall times connected to the line wires I I9 and I22 by wires I51 andi553, respectively. A wire I59 connects the other terminal of thesecondary I55 to one terminal of field winding I38 and the otherterminal of the latter is connected by a wire I60 to a brush I5I bearingon drum I53. This drum has a surface which is of conducting material I62(suitably insulated from shaft 39) except for the portions I63, I64 andI55 which are of insulating material. The brush IIiI presently rides onthe conducting part I52 and is thereby connected to a crush I55, whenthe control motor is in its low rate position. Brush I55 is connected bya wire I51 to the contact I53. The contact I52 is connected by a wireI66 to a brush I59, presently engaging the insulating part I53, withwhich another brush IE5 is engaged. Brush I16 is connected by a wire IIIto wire I54 and thus to the same terminal of secondary I55 that isconnected to thermostat switch I5I.

It will be seen that, with the parts positioned as shown, no circuitexists to the field I38 of the control motor. However. if the outdoortemperature should drop below the selected predetermined value, switch I5I will engage its contact I53 and close a starting circuit to fieldI38. This circuit may be traced as follows, from secondary I55, by wireI55, switch I5I, contact I53. wire I51, brush I58, conductor I52 on drumI53, brush IEI, wire I56, field winding I 38 and wire I59 to the otherterminal of secondary I55. As soon as the drum I52 has turned through asmall angle the brushes I59 and I15 will engage the conducting part I62of drum I 53 and a holding circuit will be closed to the field windingI58, which circuit shunts out the switch I5I. This holding circuit maybe traced as follows, from one terminal of secondary I55, by wire I5 3,wire I1I, brush I10, conductor I52 of drum I43, brush I6I, wire I60,field winding I38 and wire I59 to the other terminal of secondary I55.When the drum I63 has turned one half a revolution, brush I10 willengage insulating part I65 and break the holding circuit and brush I55will engage insulating part I65 and break the starting circuit so thatthe control motor comes to rest in its high rate position even thoughswitch I5I engages contact I53.

It will also be noted that the brush I69 will be connected by drum partI62 to brush I6I, so that another starting circuit to the field windingcan be established when the switch I5I engages contact I52. Thisstarting circuit is as follows, from one terminal of secondary I55, bywire I54, switch I 5I, contact I52, wire I68, brush I69, conducting partI62, brush I6I, wire I60, field winding I38 and wire I59 to the otherterminal of secondary I55. The closing of this starting circuit willturn drum I43 in the same direction as before. After the drum has turnedthrough a small angle, brush I16 will ride off insulating part I64 andengage conducting part I52, whereby it is connected to brush I6I, toestablish a holding circuit by which the starting circuit is shuntedout. This second holding circuit is as follows, from one terminal ofsecondary I55, wires I54 and I'll, brush I16, conducting part I62, brushI6I, wire I60, field winding I38 and wire I59 to the other terminal ofsecondary I 55. The motor 31 will continue to turn until it hascompleted its second half revolution when brushes I69 and I10 willengage the insulating part I63 and open both the second holding circuitand the second 13 starting circuit to top the motor 31. Also, the brushI65 will be engaged with conducting part I62 to connect thermostatcontact I53 to brush I6I, whereby to enable the first starting circuitto be re-established, whenever the outdoor thermostat II engages contactI53.

The burner described will have its firing rate automatically controlledby the switch I5 I, which as described responds to outdoor temperaturebut which is capable of responding to temperature at other locations ifdesired. When the switch I5I engages the hot contact I52, the inductiveshunt I31 will be connected in circuit with pump coil 51, whereby thecurrent fiow will be divided part, say one-quarter, through the shuntand part, say three-quarters, through the coil 51, and the reducedcurrent through the coil will cause the pump to deliver oil at the lowerof the two predetermined rates. Simultaneously with the connection orthe inductive shunt I31 in circuit with the pump coil 51, the controlmotor 31 will cause the damper 28 to move to its low rate position toreduce the rate of air flow in tube II to the proper value to producewith the lowered rate of oil flow a good combustible mixture. When theswitch I5I engages the cold contact I53, the control motor 31 will causethe circuit to shunt I31 to be opened to increase the oil flow to thehigher of the two predetermined rates and the damper 28 to be moved toincrease the rate of air flow to that necessary to produce goodcombustion with the increased rate of air flow.

In many cases, it will be satisfactory if the shift from one firing rateto another is effected manually. The manual control is showndiagrammatically in Fig. 11, which is the same as Fig. 10 except thatthe control motor 31, the step-down transformer I5IiI55, the wires I51and I58, the outdoor thermostat switch I5I and all the electricalconnections between this motor, switch and transformer are omitted andthe switch, comprising brushes I46 and I41 and drum I42, is replaced bya switch I12, the terminals of which are respectively connected by wiresI13 and I14 to one terminal of the coil 51 and one terminal of shuntI31, the other terminals of the shunt and coil being connected togetherby a wire I15. The switch I12, when manually closed and opened, willrespectively connect and disconnect the inductive shunt I31 in circuitwith the pump coil 51 and cause the latter to operate at the selectedlow and high predetermined rates, respectively, in the same manner asbefore.

The switch I12 is shown in Fig. 8 as a micro switch, suitably supportedfrom the side wall 8 of the fan casing 2. This switch tends to openautomatically. It is shown in closed position, its plunger having beenmoved to such position by the outer end of spring arm I11, the inner endof which is fixed to a hand lever I18, loosely mounted on one end of thedamper shaft 29. Adjacent the lever I18 and fixed to the shaft 29, isthe described crank arm 36, which as before is actuated by spring 35,tending to move the damper 28 into its high rate position. The hub ofcrank arm 30 is connected to the lever I18 by a torsion spring I80. Thelever moves the shaft 29 through the torsion spring I80 to carry thedamper 28 from high rate to low rate position. After the damper hasengaged the low rate stop 3I, the hand lever I18 may, because of sprinI80, continue to move until it is so positioned that spring-pressed pinI8! slidably mounted therein aligns with a hole I82 in wall 8 of fancasing 2, whereupon the pin I8I will enter the hole and keep the leverin its low rate position. When this pin IBI is pulled back to releaselever I18, the spring 35 will move the damper 28 back into engagementwith the high rate stop 30 and, at the same time, through spring I andcrank arm 38 move hand lever I18 to lift the spring I11 sufiiciently toallow switch I12 to open and disconnect the inductive shunt I31 from thecircuit of the pump coil 51.

With either form of the invention the oilrate-varying means and theair-rate-varying means are interconnected so as to operatesimultaneously and effect corresponding change in the two components ofthe combustible mixture. The change in firing rates may be effectedwholly automatically, as in the first form of the invention, ormanually, as in the second form of the invention. The invention alsoaffords a particular means for varying the pumping rate of anelectromagnetically-controlled pump, which means will operate with, andnot adversely affeet, a pressure regulator of the type described, whichtends to maintain the output current at a substantially constant value.The invention enables the regulator to maintain the output currentconstant but provides a shunt circuit through which part of the currentmay be diverted when it is desired to lower the current flow through themagnet coil to secure a lower pumping rate.

What is claimed is:

1. An atomizing means for liquids, selectively operable at a pluralityof rates, comprising, a high-pressure mechanical-atomizing nozzle, avariable-stroke reciprocating-piston pump having an inlet and acheck-valve-controlled outlet, a valveless conduit connecting saidoutlet and nozzle, an electromagnet controlling the reciprocation of thepiston of said pump and including a core and coil, a circuit for saidcoil adapted for connection to an alternating current supply, aninductance having substantially the same power factor as said coil andan impedance of the same order of magnitude as said coil, saidinductance being connected in shunt with the coil in said circuit, aswitch for closing and opening the shunt and connecting said inductanceto or disconnecting it from said circuit thereby selectively controllingthe rate at which liquid is atomized, whereby when said switch is closeda part of the current may be caused to flow through said coil and therest through said inductance and when said switch is open all thecurrent may be caused to flow through said coil, an electrical regulatorin said circuit for maintaining the total current in said circuitsubstantially constant at one predetermined value over a predeterminedrange of variations in voltage of said supply, said regulator byregulating the current also regulating the stroke of the piston of saidpump and thus the pumping rate thereof and maintaining the averagepressure of the liquid supplied to said nozzle constant either at a highvalue, when said switch is opened, or at a lower value, when said switchis closed.

2. In a dual-firing rate oil burner, wherein a fan, driven by anelectric motor, supplies air for combustion through a tube, in theoutlet end of which is a high-oil-pressure mechanical-atomizing nozzle,and a valve is provided, movable between two positions, to vary the rateat which air is supplied by the fan to the tube from a high rate to alower rate and wherein oil is supplied to the nozzle by avariable-stroke reciprocatingpiston pump, actuated by an electromagnet,in-

eluding a coil, having an energizing circuit, adapted for connection toan alternating current source; an inductance having substantially thesame power factor as said coil and an impedance of the same order ofmagnitude as said coil, said inductance being connected in shunt withthe coil in said circuit, a switch for closing and opening the shunt andconnecting said inductance to or disconnecting it from said circuitthereby selectively controlling the rate at which liquid i atomized,whereby when said switch is closed a part of the current may be causedto iicw through said coil and the rest through said inductance and whensaid switch is open all the current may be caused to flow through saidcoil, an electrical regulator in said circuit for maintaining the totalcurrent in said circuit substantially constant at one predeterminedvalue over a predetermined range of variations in voltage of saidsupply, said regulator by regulating the current also regulating thestroke of the piston of said pump and thus the pumping rate thereof andmaintaining the average pressure of the liquid supplied to said nozzleconstant either at a high value, when said switch is opened, or at alower value, when said switch is closed, and a member for simultaneouslymoving said switch and valve to close the switch when the valve is inits secondnamed position and open the switch when the valve is in itsfirst-named position.

3. In a dual-firing rate oil burner, wherein a fan, driven by anelectric motor, supplies air for combustion through a tube, in theoutlet end of which is a high-oil-pressure mechanical-atomizing nozzle,and a valve is provided, movable be tween two positions, to vary therate at which air is supplied by the fan to the tube from a high rate toa lower rate and wherein oil is supplied to the nozzle by avariable-stroke reciprocatingpiston pump, actuated by an electromagnet,including a coil, having an energizing circuit, adapted for connectionto an alternating current source; a switch in said circuit actuated byand responsive to the speed of the fan motor for 16 closing and openingsaid circuit when the speed of the motor respectively increases to andfalls below a predetermined value, an inductance having substantiallythe same power factor a said coil and an impedance of the same order ofmagnitude as said coil, said inductance being connected in shunt withthe coil in said circuit, a switch for closing and opening the shunt andconnecting said inductance to or disconnecting it from said circuitthereby selectively controlling the rate at which liquid is atomized,whereby when said switch is closed a part of the current may be causedto flow through said coil and the rest through said inductance and whensaid switch is open all the current may be caused to flow through saidcoil, an electrical regulator in said circuit for maintaining the totalcurrent in said circuit substantially constant at one predeterminedvalue over a predetermined range of variations in voltage of saidsupply, said regulator by regulating the current also regulating thestroke of the piston of said pump and thus the pumping rate thereof andmaintaining the average pressure of the liquid supplied to said nozzleconstant either at a high value, when said switch is opened, or at alower value, when said switch is closed, and a member for simultaneouslymoving said switch and valve to close the switch when the valve is inits second-named position and open the switch when the valve is in itsfirstnamed position.

PHILIP H. BILLS.

JOSEPH A. LOGAN.

THEODORE J. MESH.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,923,614 Clarkson Aug. 22, 1933 1,955,797 Engstrom Apr. 24,1934 2,117,512 Scott May 17, 1938 2,319,934 Korte et al. May 25, 19432,362,259 Findley Nov. 7, 1944 2,494,837 Simmons Jan. 17, 1950

